Utility companies, power distribution companies and similar entities in the United States are currently handicapped by an inability to accurately monitor in real time the state of power lines and distribution grids. Thus, problems and inefficiencies often go undetected, resulting in needless expenditures and waste. The present invention is designed to address and rectify this situation.
Electrical power in the United States is largely transmitted in the form of alternating current at a predetermined frequency most frequently 60 Hz. As is known, when current passes through a transmission line, it generates an electro magnetic field that varies in frequency and intensity with the current flowing through the line. These fluctuations plotted against time, are in the form of a sinusoidal wave. As is also known, reflected waves traveling in the opposite direction of the current flow include harmonics, transients and variations that reflect conditions down the transmission line. Such harmonics, transients and variations in current and voltage as a function of time can be observed, characterized and analyzed using known mathematical techniques. See Arrillaga, Power System Harmonic Analysis (John Wiley & Sons, 1996), chapters 4, 6, 7 and 9. Events occurring to the transmission line such as shorts, lightning strikes, changes in load and similar conditions also generate transient variations that are reflected in the electro magnetic field surrounding the transmission line. The magnitude and frequency of such harmonics, transients and variations can be measured and in accordance with the invention, the data collected and processed to reflect events and occurrences affecting the transmission grid. Thus, in accordance with the invention, monitoring and measuring changes in the electro magnetic field surrounding the transmission line, enables real time or near real time monitoring of the state of the transmission line. The state of the line may be charged with high or low voltage, or be without current or charge. As used herein the terms “real time” and “near real time” refers to time required for a computer to receive and process one or more input data streams and output a signal or value based upon the input data. Thus, in most instances, “real time” will be measured in seconds or fractions of a second.
Stewart U.S. Pat. No. 5,982,276, the disclosure of which is hereby incorporated by reference, describes a system for communicating information between subscribers over power transmission lines which normally convey electrical power to a plurality of diverse electrical sites for providing electrical power to electrical devices disposed at these diverse electrical sites. This communication system makes use of an inductive coupling to receive the transmitted information from the magnetic field surrounding the power transmission line. The inductive coupler is preferably a ferroceramic type of inductive coupler having a sensitivity such as 10−23 volts. The present invention utilizes inductive couplers to detect changes in the electromagnetic field surrounding a transmission line, measures the changes and utilizes the data to identify conditions and events occurring on the transmission line.